Fin and heat exchanger comprising the same

ABSTRACT

A corrugated fin includes connection segments each of which is formed with louvers. Substantially circular arc segments are connected with the connection segments alternatively in a substantially longitudinal direction such that corrugations are formed and the arc segments form respective crests and troughs of the corrugations. 0≦H 2 ≦(H 1 −2R+2R sin β)/cos β, in which “H 2 ” is a length of the corresponding louver, “H 1 ” is a height of the fin, “R” is a radius of the corresponding arc segment, and “β” is an angle of inclination of the corresponding connection segment. A heat exchanger includes a first header, a second header spaced apart from the first header, and tubes spaced apart from each other and each of which is connected between the first and second headers in fluid communication therewith. Fins are each disposed between adjacent tubes.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and benefit of the filing date of Chinese Patent Application 201010215928.3 entitled “Fin and Heat Exchanger Comprising the Same” and filed on Jun. 29, 2010.

BACKGROUND OF INVENTION

1. Field of Invention

The invention relates, generally, to a fin and, more specifically, to a corrugated fin and a heat exchanger that includes the fin.

2. Description of Related Art

When a heat exchanger is used as an evaporator, a lot of condensate may be accumulated on surfaces of the fins due to structure limitation of the conventional corrugated fin, thus not only influencing the heat-transfer performance of the heat exchanger, but also increasing the air resistance of the surface of the heat exchanger and, thereby, the power consumption of the air blower. Particularly, when the conventional fin is used in an inverted V-shaped or flat-plate-shaped heat exchanger, an inclination angle is formed between the surface of the heat exchanger and a horizontal plane. Because the condensate is accumulated on the surface of the heat exchanger during operation, the condensate may directly drop into an air pipe below the heat exchanger from the surface of the heat exchanger. In this way, water leakage may occur in the unit using the heat exchanger, the air pipe may be corroded, and bacteria may breed in the corroded air pipe, thus shortening the service life of the unit (such as an air conditioner) and causing damage to human health.

Thus, there is a need in the related art for a corrugated fin that is used for a heat exchanger and has a good water-drainage performance. More specifically, there is a need in the related art for such a fin such that no condensate drops directly from a surface of the heat exchanger during operation and stoppage, good heat-exchange performance is ensured, and air-side-pressure drop is not too large. There is a need in the related art also for a heat exchanger that uses the fin.

SUMMARY OF INVENTION

The invention overcomes the disadvantages in the related art in a corrugated fin that includes connection segments each of which is formed with louvers. Substantially circular arc segments are connected with the connection segments alternatively in a substantially longitudinal direction such that corrugations are formed and the arc segments form respective crests and troughs of the corrugations. 0≦H₂≦(H₁−2R+2R sin β)/cos β, in which “H₂” is a length of the corresponding louver, “H₁” is a height of the fin, “R” is a radius of the corresponding arc segment, and “β” is an angle of inclination of the corresponding connection segment.

The invention overcomes the disadvantages in the related art also in a heat exchanger that includes a first header, a second header spaced apart from the first header, and tubes spaced apart from each other and each of which is connected between the first and second headers in fluid communication therewith. Fins are each disposed between adjacent tubes.

One advantage of the fin and heat exchanger of the invention is that they have good water-drainage performance.

Another advantage of the fin and heat exchanger of the invention is that no condensate drops directly from a surface of a heat exchanger during operation and stoppage.

Another advantage of the fin and heat exchanger of the invention is that good heat-exchange performance is ensured.

Another advantage of the fin and heat exchanger of the invention is that air-side-pressure drop is not too large.

Another advantage of the fin and heat exchanger of the invention is that normal air-side-pressure drop is ensured.

Another advantage of the fin and heat exchanger of the invention is that formation or accumulation of condensate drops on the louvers and a surface of the fins may be reduced or eliminated so that the condensate may flow onto the tubes along the fins and gather into a water-collecting pan along the tubes rather than drop into the air pipe.

Another advantage of the fin and heat exchanger of the invention is that no water leakage may occur in the unit using the heat exchanger.

Another advantage of the fin and heat exchanger of the invention is that the air pipe may not be corroded.

Another advantage of the fin and heat exchanger of the invention is that bacteria may not breed in a corroded air pipe.

Another advantage of the fin and heat exchanger of the invention is that service life of the unit is lengthened.

Another advantage of the fin and heat exchanger of the invention is that damage to human health is not caused.

Another advantage of the fin and heat exchanger of the invention is that accumulated water at the arc segments may be reduced so that no water may drop from the arc segments.

Other objects, features, and advantages of the invention are readily appreciated as the same becomes better understood while reading the subsequent description taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF EACH FIGURE OF DRAWING OF INVENTION

FIG. 1 is schematic view of a portion of a corrugated fin according to an embodiment of the invention;

FIG. 2 is a sectional view of the fin taken along line “B-B” of FIG. 1;

FIG. 3 is a “principle force” diagram of condensate on a connection segment of the fin shown in FIG. 1;

FIG. 4 shows a relationship among a length of a louver, capacity of the fin, and air velocity on a surface of the fin;

FIG. 5 shows a relationship among a length of a louver, air resistance of the fin, and air velocity on a surface of the fin;

FIG. 6 is a relational graph among a radius of an arc segment, adsorption force of condensate, and a sum of gravity of the condensate and pushing force of air;

FIG. 7 is a schematic view of a heat exchanger according to an embodiment of the invention;

FIG. 8 is a perspective view of a heat exchanger according to another embodiment of the invention;

FIG. 9 is a side view of the embodiment of the heat exchanger shown in FIG. 7 in use; and

FIG. 10 is a side view of the embodiment of the heat exchanger shown in FIG. 8 in use.

DETAILED DESCRIPTION OF EMBODIMENTS OF INVENTION

As shown in FIGS. 1 through 2, a corrugated fin 4 according to an embodiment of the invention includes substantially circular arc segments 41 and connection segments 42. The arc segments 41 are connected with the connection segments 42 alternatively in a substantially longitudinal direction such that corrugations are formed and the arc segments 41 form respective crests and troughs of the corrugated fin 4. In other words, the connection segment 42 can be referred as a “fin wall” of a corrugation of the corrugated fin 4, and the arc segment 41 can be referred as a “crest” and “trough” of a corrugation of the corrugated fin 4.

Each connection segment 42 is formed with louvers 43. In some embodiments, for example, the corrugated fin 4 may be made of aluminum material. However, those having ordinary skill in the related art should appreciate that the invention is not limited to this.

In the example shown in FIGS. 1 through 2, the connection segment 42 is a substantially straight segment. It should be appreciated that the invention is not limited to this. For example, the connection segment 42 may also have an actuate shape.

A portion of the corrugated fin 4 is shown in FIG. 1. It should be appreciated that the corrugated fin 4 may have any suitable length in the longitudinal direction (i.e., an “up” and “down” direction in FIG. 1). In other words, the corrugated fin 4 may have any suitable number of corrugations.

As shown in FIGS. 1 through 2, to improve the heat-exchange performance, louvers 43 are formed in each connection segment 42. The louver 43 may be formed by cutting and bending a certain portion of the connection segment 42 to form a vane 431 and an opening 432. For example, a portion of the connection segment 42 is cut and turned-over from a surface of the connection segment 42, in which “α” is a “louver” angle (i.e., an angle of inclination of the vane 431 with respect to the plane of the connection segment 42, as shown in FIG. 2), “W” is an interval between adjacent louvers 43 (i.e., length of a substantially straight line between adjacent louvers 43 in a “transversal” direction to a “length” direction of the louver 43), “H₂” is a length of the louver 43 (i.e., a dimension of the louver 43 in a “right” and “left” direction in FIG. 1), and “S” is a “vane” distance (i.e., distance of a straight line between the adjacent vanes 43, as shown in FIG. 2). A fin pitch “P” is a spacing between adjacent crest and trough (i.e., adjacent arc segments 41). In other words, the fin pitch “P” is a distance of a straight line between two points with the same phase relationship of the corrugated fin 4 in the longitudinal direction.

If the heat exchanger is used as an evaporator, when the heat exchanger is the flat-plate-shaped heat exchanger and inclined with respect to a horizontal direction (as shown in FIG. 9) or a bent heat exchanger (as shown in FIG. 10), during operation or stoppage, the condensate on the surface of the corrugated fin 4 may directly drop from the surface of the corrugated fin 4.

More particularly, the condensate may be accumulated on the surface of the corrugated fin under the following conditions: 1) the smaller the radius “R” of the arc segment is, the greater the surface tension of the condensate is so that the condensate tends to be accumulated on the arc segment; 2) the smaller the fin pitch “P” of the fin is, the more condensate tends to accumulate between adjacent connection segments; and 3) the smaller the interval “W” between adjacent louvers is, the more condensate tends to accumulate between adjacent louvers.

The heat-exchange performance, air resistance, and accumulated water on the surface of the heat exchanger using the corrugated fin have direct relationship to the louver length “H₂.” The larger the louver length “H₂” of the louver is, the better is the heat-exchange performance and the larger is the air resistance. Consequently, more water is accumulated on the fin.

As shown in FIGS. 4 through 5, when the louver length “H₂” is greater than a length “L” of the connection segment 42 (that is, the louver 43 is extended into the arc segment 41), the increasing trend of the performance of the heat exchanger becomes weak and the increasing trend of the air resistance becomes strong.

It may be obtained from the geometry that L=(H₁−2R+2 R sin β)/cos β.

The larger the louver length “H₂” is, the more water accumulated on the louver is and the easier the water drops. For this, in an embodiment, 0≦H₂≦(H₁−2R+2R sin β)/cos β is set for preventing water from dropping downward from the fin, in which “H₂” is the louver length, “H₁” is the height of the fin, “R” is the radius of the arc segment, and “β” is the inclination angle of the connection segment.

To ensure that no water drops directly from the arc segments 41, the radius “R” shall be small enough. Considering actual use, there is a limit to decrease the radius “R,”—that is, the radius “R” cannot be decreased infinitely so that the condensate is unavoidable to accumulate on the arc segments 41. Therefore, in an embodiment, the surface tension of water is increased, and the weight of the water is reduced.

The water may not drop directly from the arc segment 41 if the radius “R” is less than or equal to 0.85 mm.

The adsorption force of the condensate to the arc segment 41 may be calculated by the formula “F=πRcσ/180,” in which “F” is the adsorption force, “σ” is the surface-tension coefficient, “c” is the central angle of the arc segment, and “R” is the radius of the arc segment.

The weight of the condensate on the arc segment may be calculated by the formula “G=(4/3)πR³ρg,” in which “ρ” is the density of the condensate, “g” is the acceleration of gravity, and “R” is the radius of the arc segment.

At the same time, if the air blows downward, the air applies a downward-pushing force “M” to the accumulated water on the corrugated fin 4 and “M=πR²μ²/2ρ_(k),” in which “ρ_(k)” is the density of the air, “R” is the radius of the arc segment, and “μ” is the flowing velocity of the air.

To ensure that no water drops from the arc segment 41, the formula “F≧G+M” shall be satisfied.

As shown in FIG. 4, the adsorption force shall be greater than or equal to the sum of the gravity of water and pushing force of the air to avoid dropping of the condensate from the arc segment 41—that is, the radius “R” of the arc segment 41 shall be less than or equal to about 0.85 mm. Meanwhile, considering the machinability, in an embodiment, the radius “R” is greater than or equal to about 0.1 mm.

Under the above conditions, when the air blows upward, it can be also ensured that no condensate drops from the arc segment 41.

Therefore, by setting the radius “R” in a range of about 0.1 mm to about 0.85 mm, the adsorption force of the condensate on the arc segment 41 may be greater than the sum of the gravity of the condensate and pushing force of the air, thus avoiding dropping of the condensate from the arc segment 41. Therefore, the water is prevented from dropping downward into the air pipe from the arc segment 41.

For the connection segments 42 of the corrugated fin 4, if the condensate thereon may not be removed in time, it may drop from the connection segments 42 into the air pipe. In this way, the water leakage may occur in the unit using the heat exchanger, the air pipe may be corroded, and bacteria may breed in the corroded air pipe, thus shortening the service life of the unit and causing damage to human health.

To ensure that no water drops from the connection segments 42, as shown in FIGS. 1 and 3, the inclination angle “β” of the connection segment 42 shall be big enough. Therefore, the condensate flows downward along the connection segment 42 and, consequently, into the water-collecting pan (not shown) along the tube 3 so that no water is accumulated on and dropped from the connection segment 42. Meanwhile, the fin pitch “P” shall be large enough.

When the down-sliding force of the water on an inclined surface of aluminum-alloy fin 4 is greater than the friction force (that is, mg sin β>fN, in which “f” is the friction coefficient and “β” is the inclination angle of the connection segment, as shown in FIG. 1), water may slide downward. As shown in FIG. 3, according to the force analysis, the equation “N=mg cos β” is obtained, and the inequality “tan β>f” is obtained by substituting the equation into the formula “mg sin β>fN.” When the inclination angle “β” is greater than or equal to about 5°, water starts to flow downward on the surface of connection segment. Therefore, the inclination angle “β” shall be greater than or equal to about 5°. Meanwhile, considering machinability, “β” shall be in a range of about 5° to about 20°.

When the fin pitch “P” is substantially larger than about 2.5 mm, no condensate presents between adjacent connection segments 42. However, the larger the fin pitch “P” is, the lower the performance of the heat exchanger is. Meanwhile, considering machinability, in an embodiment, the fin pitch “P” is substantially in a range of about 2.8 mm to about 7 mm.

The accumulated water between adjacent louvers 43 is mainly caused by the surface tension of water. If the vane distance “S” of the louver 43 is increased, the surface tension of water between the adjacent louvers 43 may be reduced or eliminated, thus decreasing or eliminating the accumulated water between the adjacent louvers 43. The surface tension of water between the adjacent louvers 43 may be effectively decreased if the vane distance “S”=W×sin α≧0.57 mm. For this reason, in an embodiment, W×sin α≧0.6 mm. More particularly, 0.8 mm≦W×sin α≦3.0 mm.

With the corrugated fin 4 according to an embodiment of the invention, the water-drainage performance is improved, and dropping of the condensate into the air pipe from the surface of the heat exchanger using the corrugated fin 4 may be reduced or eliminated, thus prolonging the life of the unit and reducing the harm of the bacteria.

The heat exchanger according to an embodiment of the invention is now described with reference to FIGS. 7 and 8. As shown in FIG. 7, the heat exchanger according to an embodiment of the invention includes a first header 1, a second header 2, tubes 3, and corrugated fins 4.

The second header 2 is spaced apart from and substantially parallel to the first header 1. The tubes 3 are arranged and spaced apart from each other in a direction substantially parallel with the axial direction of the first and second headers 1, 2. Two ends of each tube 3 are connected respectively to the first and second headers 1, 2 to communicate the first and second headers 1, 2. The fins 4 are disposed between adjacent tubes 3, in which the corrugated fins 4 may be ones described with reference to the above embodiments.

In one embodiment, the tube 3 may be a flat tube. For example, the shape of the cross-section of the tube 3 may be a rectangle, an oblong presenting flat sides interconnecting two round ends, or a flat ellipse.

In one example, the heat exchanger may have a flat-plate shape. When used as an evaporator, the heat exchanger is inclined with respect to the horizontal plane, and, as shown in FIG. 9, air blows from an air outlet to the surface of the heat exchanger in a direction “A.” As described above, because no condensate drops, performance of the heat exchanger may not be influenced, the heat exchanger may not be damaged, and harm of the bacteria may be avoided.

As shown in FIG. 8, in some embodiments, the heat exchanger has a bent structure. In a specific example, each tube 3 includes two substantially straight segments 31 and a bent segment 32 connected between and twisted relative to the two straight segments 31 by a predetermined angle. And, each fin 4 is only disposed between adjacent straight segments 31. In other words, no fins are disposed between adjacent bent segments 32.

The heat exchanger having a bent structure is not limited to the above embodiments. For example, the bent heat exchanger may be formed by two flat-plate-shaped heat exchangers connected in series via a connecting pipe and forming a certain intersection angle therebetween.

With the heat exchanger having a bent structure according to an embodiment of the invention, in use, the heat-exchanger portions on two sides are inclined at a certain angle with respect to the horizontal plane, and, as shown in FIG. 10, air blows from an air outlet to the heat exchanger in a direction “A.” As described above, because no condensate drops, no water leakage may occur, the air pipe may not be corroded, and bacteria may not breed in the corroded air pipe, thus lengthening the life of the unit (such as an air conditioner) without causing damage to human health.

The invention has been described in an illustrative manner. It is to be understood that the terminology that has been used is intended to be in the nature of words of description rather than of limitation. Many modifications and variations of the invention are possible in light of the above teachings. Therefore, within the scope of the appended claims, the invention may be practiced other than as specifically described. 

1. A corrugated fin comprising: a plurality of connection segments each of which is formed with a plurality of louvers; and a plurality of substantially circular arc segments connected with said connection segments alternatively in a substantially longitudinal direction such that a plurality of corrugations are formed and said arc segments form respective crests and troughs of the corrugations, wherein 0≦H₂≦(H₁−2R+2R sin β)/cos β, in which “H₂” is a length of corresponding said louver, “H₁” is a height of said fin, “R” is a radius of corresponding said arc segment, and “β” is an angle of inclination of corresponding said connection segment.
 2. A corrugated fin as set forth in claim 1, wherein said radius “R” is no less than about 0.1 mm and no greater than about 0.85 mm.
 3. A corrugated fin as set forth in claim 1, wherein said angle of inclination “β” is no less than about 5°.
 4. A corrugated fin as set forth in claim 3, wherein said angle of inclination “β” is no greater than about 20°.
 5. A corrugated fin as set forth in claim 1, wherein W×sin α≧0.6 mm, in which “W” is an interval between adjacent ones of said louvers and “α” is an angle of corresponding said louver.
 6. A corrugated fin as set forth in claim 1, wherein a pitch “P” of said fin is greater than about 2.5 mm.
 7. A corrugated fin as set forth in claim 6, wherein said pitch “P” is no less than about 2.8 mm and no greater than about 7 mm.
 8. A corrugated fin according to claim 6, wherein W×sin Δ≧0.6 mm, “W” is an interval between adjacent ones of said louvers, and “α” is an angle of corresponding said louver.
 9. A corrugated fin as set forth in claim 8, wherein 0.8 mm≦W×sin α≦3.0 mm.
 10. A heat exchanger comprising: a first header; a second header spaced apart from said first header; a plurality of tubes spaced apart from each other and each of which is connected between said first and second headers in fluid communication therewith; and a plurality of corrugated fins each of which is disposed between adjacent ones of said tubes and includes: a plurality of connection segments each of which is formed with a plurality of louvers; and a plurality of substantially circular arc segments connected with said connection segments alternatively in a substantially longitudinal direction such that a plurality of corrugations are formed and said arc segments form respective crests and troughs of the corrugations, wherein 0≦H₂≦(H₁−2R+2R sin β)/cos β, in which “H₂” is a length of corresponding said louver, “H₁” is a height of said fin, “R” is a radius of corresponding said arc segment, and “β” is an angle of inclination of corresponding said connection segment.
 11. A heat exchanger as set forth in claim 10, wherein said tube includes two substantially straight segments and a plurality of bent segments each of which is connected between and twisted relative to said straight segments by a predetermined angle and none of said fins is disposed between adjacent ones of said bent segments.
 12. A corrugated fin as set forth in claim 11, wherein said radius “R” is no less than about 0.1 mm and no greater than about 0.85 mm.
 13. A corrugated fin as set forth in claim 11, wherein said angle of inclination “β” is no less than about 5°.
 14. A corrugated fin as set forth in claim 13, wherein said angle of inclination “β” is no greater than about 20°.
 15. A corrugated fin as set forth in claim 11, wherein W×sin α≧0.6 mm, in which “W” is an interval between adjacent ones of said louvers and “α” is an angle of corresponding said louver.
 16. A corrugated fin as set forth in claim 11, wherein a pitch “P” of said fin is greater than about 2.5 mm.
 17. A corrugated fin as set forth in claim 16, wherein said pitch “P” is no less than about 2.8 mm and no greater than about 7 mm.
 18. A corrugated fin according to claim 16, wherein W×sin α≧0.6 mm, “W” is an interval between adjacent ones of said louvers, and “α” is an angle of corresponding said louver.
 19. A corrugated fin as set forth in claim 18, wherein 0.8 mm≦W×sin α≦3.0 mm. 